Magnetic separator



' R. H. STEARNS 2,306,648

MAGNETIC SEPARAIOR I Filed July 13, 1940 3 Sheets-Sheet 1 cv a .m s m v v a MM. A w a m a z 4 M 1 0 5w l a 2 5 3 v fl 0 H u x 3 4w z z 6 0 7 n a 9 Q o 9 3 y Dec. 29, 1942.

Dec. 29, 19412. R. H. STEARNS MAGNETIC SEPARATOR Filed July 15, 1940 3 Sheets-Sheet 2 flaw n? W ATTORNEY.

Dec. 29, 1942. R. H. STEARNS MAGNETIC SBPARATOR Filed July 15, 1940 3 Sheets-Sheet 3 Patented Dee. 29, 1942 UNITED STATS TENT 0mm MAGNETIC SEPARATOR Roswell H. Stearns, Wauwatosa, Wis., assignor to Stearns Magnetic Mfg. 00., Milwaukee, Wis., a corporation of Wisconsin Application July 13, 1940, Serial No. 345,379

10 Claims.

This invention relates to magnetic separators and is particularly directed to magnetic separators of the type in which there is a gravity feed 7 of the material past stationary poles.

In magnetic separators, particularly those which have stationary poles and a gravity feed of material past the poles, it is necessary to have the adjustment of the poles both as to angularity and spacing as well as field strength so that the separator can be adjusted to meet the exact demands for the particular material to be operated upon.

Objects of this invention, therefore, are to provide a magnetic separator in which the poles may be adjusted both as to angularity and as to spacing, in which the dividing means located below the lower pole may also be adjusted to correspond to the adjustment of the poles, and in which a non-magnetic shielding means may be adjusted.

Further objects are to provide a magnetic separator which has the adjustable poles and which has a feeding means carried by the upper adjustable pole so that the relative adjustment of the feeding means with respect to the upper pole is not varied though the upper pole may be adjusted as desired.

In greater detail, further objects are to provide a magnetic separator in which a unitary feeding means is carried by the upper pole of the separator, the feeding means itself being adjustable to vary the rate of feed and also the clearance between the feeding chute or vibrating chute and the adjacent portion of the separator, the

'ieeding chute being of the vibratory type whose throw or extent of vibration is adjustable, and in which means are provided which are independently adjustable for vibrating a non-magnetic shielding plate over the poles.

Further objects are to provide a magnetic separator in which the field structure and the poles have a socketed connection so that a large contact area is always provided between the adjustable poles and the field structure to thereby secure the minimum reluctance at this surface of contact,

In this art the usual practice is for a prospective purchaser to submit a sample of the material which he wishes to separate into the magnetic This invention and non-magnetic components. provides a universally adjustable separator which may be adjusted to effect the desired separation eitherin a single stage or in successive stages, a laboratory or test machine being utilized to effect the separation and being universally adjustable as hereinabove set forth so that the exact adjustment for the particular material may be readily obtained. If the material is to be separated in a series of stages or, in other words, with a series of successive separations, the adjustment for the first stage is determined by the laboratory or test machine by appropriately adjusting its parts. Thereafter the non-magnetic material, which in reality has a mixture of lesser magnetic material and non-magnetic material, is again passed through the laboratory machine after suitable adjustment has been made corresponding to the second stage of magnetic separation. This process is continued for as many v stages as may be desired. Thereafter the commercial machine has each of its stages adjusted to correspond to the adjustment of the test or laboratory machine so that each stage of the composite or multiple separator is accurately adjusted to correspond precisely to that obtained when the laboratory machine was employed.

There is thus the maximum precision obtained in the adjustment of the commercial machine. Thereafter this commercial machine, properly adjusted as hereinabove set forth, is shipped to the customer and is installed and goes into immediate operation with full assurance that it has been properly and accurately adjusted for the particular needs of the customer and for the particular material that it is t operate upon.

It sometimes happens that it is desirable to produce a commercial machine having the relative adjustments permanently made, thatv is to say, by the use of fixed poles properly spaced in exact accordance with that obtained by the test or laboratory machine. Either one of these two methods is employed,

It is to be noted, however, that where the commercial machine is provided for the adjustments hereinabove set forth, that if the customer subsequently wishes to operate upon a difierent material, it is possible to repeat the process hereinabove set forth and thereby obtain the correct and precise adjustments needed for the new material which is to be separated into its component parts.

This invention also contemplates the provision of amultiple stage separator in which each stage is individually adjusted either from the adjustment of the test machine or laboratory machine or by means of adjusting the multiple stage separator itself independently of the test or laboratory machine.

A further object of this invention is to provide a magnetic separator which has the adjustments hereinabove enumerated, which is suitable either for commercial operation or for test runs for different types of material, which is so made that it may be quickly adjusted for the particular test run desired, and in which there is no disturbance of the adjustment of the feeding means although there may be an adjustment of the upper pole itself so that after the feeding means has been once adjusted, it may be left undisturbed with reference to the upper pole although the upper pole may be subsequentl adjusted.

Further objects are to provide a multiple stage separator in which novel means are provided for receiving the separated material from one stage and keeping the component parts distinct and separate from each other and feeding one of the separated portions to the next stage, the separator being so made that the magnetic material for example is always discharged outwardly from the machine while the material which has to be further separated is discharged into the feeding means of the successive stage, the machine operating by a gravity feed of the material and maintaining the material spread out in a relatively thin layer as it passes from one stage to the next stage.

In greater detail, further objects are to provide a novel form of transfer chute construction for removing the separated or magnetic material outwardly from the machine and for conveying the rejected material to the next stage, the chute construction being so arranged that the rejected material is passed downwardly directly through an outwardly flowing sheet of separated material, the chute construction providing for the spreading of the rejected material into a thin and substantially uniform layer as it passes to the feeding means of the successive stage, all of these results being accomplished by means of a gravity feed and without the use of any moving conveyors.

Embodiments of the invention are shown in the accompanying drawings, in which:

Figure 1 is a fragmentary side elevation, partly in section, showing one form of the magnetic separator.

Figure 2 is an enlarged fragmentary view of the structure shown in Figure 1 with parts broken away.

Figure 3 is a fragmentary plan view of the structure shown in Figure 1 with parts broken away.

Figure 4 is a view approximately on the section line 4-4 of Figure 2, showing the dividing means which is located below the lower pole.

Figure 5 is a view, partly broken away, showing a further form of the invention.

Figure 6 is a fragmentary elevation of one of the chutes shown in Figure 5, such view being partly in section and the sectional part being approximately on the line 6-6 of Figure 5.

Figure 7 is a plan view of the chute.

Figure 8 is a fragmentary view of a further form of the invention.

Referring to Figures 1 to 4, it will be seen that the separator comprises a field structure including upper and lower cores l and 2, a rear yoke 3, and adjustable upper and lower poles indicated generally at 4 and 5. The separator may be supported in any convenient manner. One way of supporting it has been indicated, namely, the non-magnetic spider like frame work 6 located on opposite sides thereof and provided with trunnions i so that the entire separator is may be adjustably mounted in suitable supports, such as the split bearings 8. Any other suitable manner of mounting could be employed.

Exciting windings 9 are wound on the cores l and 2 and the strength of the fields may be adjusted by means of a rheostat, not shown, or in any other suitable manner.

In Figures 2 and 3 the device has been shown drawn to an enlarged scale. It will be seen that each of the cores l and 2 is provided with a cylindrical socket and that each of the adjustable poles 4 and 5 is provided with a cylindrical portion, which portions are indicated by the reference characters 4' and 5' respectively. These cylindrical portions actually contact and fit accurately within the cylindrical cavity or cut-out in the cores 1 and 2 so that a minimum of reluctance is provided at this point.

End flanges l0, see Figure 3, are welded to the end pieces of the cores as shown in such figure and bear against the ends of the poles 4 and 5. Socketed screws H extend through the side frames 6 and through the end flanges and are threaded into the poles 4 and 5. This construction provides-means whereby the poles 4 and 5 may be locked in their adjusted position.

The poles 4 and 5 are tapered and their pointed ends are located in proximity to each other as shown clearly in Figure 2. These poles may be adjusted so that the spacings between the pole tips may be varied and also so that the angularity of the poles themselves may be varied. Additionally the amount that the upper pole overhangs the lower pole may be varied in accordance with the exact requirements for the particular material to be operated upon.

Feeding means are provided and the feeding means is carried as a unitary structure from the upper pole 4 so that adjustment of the upper pole does not vary the relative adjustment of the feeding means with respect to the upper pole.

The feeding means comprises a pair of side frames I2 which have upwardly extending arched portions [3 located on opposite sides of the upper pole. These portions I3 are provided with V- shaped cut-out portions or recessed portions as indicated at I4 in Figures 2 and 3, and these cutout portions receive the ends of the pole 4, thus accurately positioning the feeding means with respect to the upper pole 4.

Suitable screws 5 extend through the side frames and into the pole 4, see Figure 2. These side frames are made of non-magnetic material and they are joined by means of an adjustable plate I6 also of non-magnetic material which supports a vibratory feed pan or member ll supported from the plate I 3 by means of leaf springs l8 and vibrated by means of any suitable vibrator. For example, the vibrator may consist of the field structure l9 which has the alternating current winding 23 and the armature 2| may be carried by the member ll. The vibrator is adjustably secured with respect to the plate 16 by means of the screws 22 which pass through slots in an angularly arranged plate 23 rigid with the plate if) so that a greater or lesser amplitude may be given the vibrating trough or member I! to thereby vary the speed of the feeding of the material. The side frames 12 may also be connected by means of a bracing rod 24 if desired to increase the rigidity of this unitary structure.

Any suitable form of hopper as indicated at 25 is provided for discharging material in a thin transverse stream into the rear portion of the trough or vibrating member 11. It is to be noted that the plate It, see Figure 3, is provided with slots 26 through which bolts 27 pass so that the plate may be adjusted forwardly or rearwardly to vary the spacing between the feeding member I? and the upper pole 4 to thereby adjust for material of different sizes. I

A non-magnetic shield 28, see Figure 2, is provided in front of both the upper and lower poles 4 and 5. In certain forms of the invention it may not be necessary to have this non-magnetic shield extend over the upper pole 4, but it is always necessary to have the non-magnetic shield extend over the lower pole and across the air gap between the poles, as will be explained hereinafter in the description of Figure 5.

This non-magnetic shield plate 28 is adjustably carried by means of a shaft 29 locked by split bearings 30 on opposite sides of the frame l2 so that its angular adjustment may be varied as required. Preferably a slight vibratory motion is imparted to this non-magnetic shield plate 28. This can readily be accomplished by providing a rubber bumper 3| on theend of an adjustable screw threaded stud 32 which passes through a lug 33 integral with the side wall of the feeding trough l1.

Preferably this construction is duplicated on opposite sides of the machine as shown in Figure 3. The adjustment of the means for vibrating the plate 28 may be made independently of the adjustment of other parts of the apparatus, for it is obvious that the lock nuts on the threaded shank 32 may be backed off and the shank adjusted to the desired position. Preferably a very slight vibratory motion is imparted to the nonmagnetic shield plate 28.

An inverted wedge-shaped dividing member 34 is adjustably carried between the side frames l2. Such member may be rigidly carried by means of the shaft 35 which extends through the side frames l2. This shaft may be provided with an adjusting hand wheel 36, see Figure 4, and with a pointer 31 cooperating with a scale 38 carried by one of the side frame members. Suitable set screws 39 are provided for locking the shaft in any adjusted position to thereby lock the dividing member 34 in its adjusted position. It is, of course, to be appreciated that all of the parts of the feeding and dividing means are made of non-magnetic material with the exception of the magnetic vibrator.

Any suitable chute as indicated at 40, see Figures 1 and 2. may be provided for carrying the non-magnetic material away from the machine, the magnetic material falling to the left of the divider 34 and the non-magnetic material falling to the right of the divider as viewed in Figure 2.

The machine may be used as a commercial machine for regular commercial separation of materials. It may also be used as a laboratory or test machine as hereinbefcre set forth. For

example, it frequently happens that a customer material and after this setting has once been obtained, both with regard to the angularity and spacing of the poles and also with regard to the adjustment of the feed and the setting.

of the divider as well as the non-magnetic shield plate, such machine may be thereafter manufactured either as an adjustable machine or as a machine with fixed parts and may then be shipped to the prospective customer.- Additionally, if a multistage separator is required, this machine may be used as a test machine for all of the different stages. For example, one set ting is made for the first stage and this setting is carefully noted. Thereafter the setting for the next stage is made and such setting carefully noted, and so on, for all of the stages required. Thereafter a composite multistage machine, such for example as shown in Figure 5, may be provided and the parts thereof may be set in accordance with that determined by this test machine.

It is to be noted particularly that the feeding means and its relative adjustment is not disturbed by adjusting the upper pole, as the feeding means is supported from the upper pole and moves with the upper pole when the upper pole is adjusted. This materially lessens the amount of time required in making the successive adjustments as hereinabove described.

Additionally it must not be lost sight of that the machine itself may be used as a commercial machine and not merely as a test machine.

In the form of the invention shown in Figure 5, a multistage separator has been illustrated. In this separator means are provided for maintaining the wide uniform spreading out of the material as it passes from stage to stage so that a very uniform and accurately graduated feed may be obtained. Further, as will be seen as the description proceeds, this machine embodies not only the multiple adjustment of the parts hereinbefore described, but also utilizes a novel form of transfer chute construction for transferring the material from stage to stage and for delivering the magnetic separated material outwardly from the machine at'each stage, the downwardly flowing material which passes to a successive stage passing through the outwardly flowing sheet of magnetic separated material at a plurality of spaced points and being spread out as it approaches the next successive stage.

Referring to Figure 5, two stages have been shown though it is to be understood that the machine may have as many stages as desired. In the form of the invention shown in Figure 5, all of the poles are shown adjustable but it is to be distinctly understood that if desired certain of the poles may be made fixed, as will appear hereinafter.

Referring to Figure 5, the upper exciting winding for the first stage is indicated at 4| and the lower exciting winding for thesecond stage is indicated at 42. These windings are formed upon the cores 43 and 44 respectively which join the upper and lower field structure indicated at 45 and 46 for the upper stage and 47 and 48 for the lower stage. These field structures are so made that the machine is duplicated on opposite sides of the center line, that is to say, each side of the upper member 45 is provided with an adjustable upper pole 49 and with an adjustable lower pole 50. Similarly the next stage is provided with a pair of upper adjustable poles 5| and with a pair of lower adjustable. poles 52, it being understood that the feeding means and chute construction is duplicated on opposite sides of the machine.

The upper pole 49 carries the feeding mecherally by the reference character 53. It is provided with a feeding chute or trough 54 with the vibrator 55 and with the small tapper 55 for the non-magnetic shield plate 51. The dividing member is indicated at 58.

The next stage is provided with its feeding means indicated generally at 59 and such feeding means may comprise the same elements as that hereinabove described, namely, the electric vibrator 68, the feeding trough 6!, the dividing member 62, and either the same or a difierent shield plate of non-magnetic material. In the form shown this shield plate is indicated at B3 and shields the lower pole only, the material being fed to the bare upper pole at this stage.

It is to be noted that this shield plate 63 is adjustable and that it is supported from and covers the lower pole and bridges the air gap. As the poles are adjusted, this shield plate is adjusted to maintain the shielding of the lower pole and the bridging of the air gap. No tapping means is needed where the shield plate does not cover the upper pole as well as the lower pole, and it will be noted that in the second stage of Figure 5 the tapping means for the non-magnetic shield plate has been omitted.

It is to be understood that if desired the field strength may be increased for successive stages and different adjustments may be had for the successive stages.

It is to be also understood that if desired, the poles may be fixed poles whose position and relative spacing and angularity may have been previously determined by the test machine heretofore described.

Figure 8 shows a structure in which fixed poles M are provided.

Returning to Figure 5, it will be seen that between successive stages a novel form of chute construction has been provided. This chute construction is formed of non-magnetic material and comprises a transversely extending trough like receiving portion or compartment 65 for the magnetic material, and a transversely extending trough like receiving portion or compartment 65 for the non-magnetic material. The non-magnetic material is fed from the receiving portion 65 through a plurality of openings 61 furnished by vertical tubular members or delivery portions 83.

These tubular members are shown in elevation in Figure 6 and Figure '7 shows a fragmentary plan view of the chute construction, a side sectional elevation being shown in Figure 5. The material discharged from the tubular members passes downwardly to a baffle 69 which serves to further spread the material cut for each of the tubular members. It is to be noted, however, that the material passing through these tubular members 68 is delivered at a plurality of spaced points onto the baflle 69 and that this non-magnetic material is discharged through the outwardly passing sheet of magnetic material which flows from the receiving portion 65 between the tubes 63 through the spaces Hi, see Figure 6, onto the apron 35 from which it is discharged outwardly of the machine. It is preferable to provide the chamber 66 with downwardly slanting tapered faces or portions H, see Figure 6, to guide the material into the tubular members 55.

The material passes from the bafiie 69 to a transverse bafile I2, see Figure 5, and this arrests its outward speed of travel. The material is discharged from the baffle 12 onto the apron l3 and from this apron it passes to the feeding trough acts as a diverting pole.

or vibratory member 8! of the next or lower stage.

It is preferable to form the chute construction as a unitary structure as indicated in Figure 5 and these chute like constructions may be carried in any suitable manner, not shown, so that they occupy the relative positions shown in Figure 5.

It is to be noted particularly that the magnetic material is discharged from each stage outwardly of the machine without the use of any traveling conveyors whatsoever, and that th non-magnetic material is passed downwardly through this outwardly traveling sheet of magnetic material and is delivered in a well distributed manner to the next feeding means. As many of these chute constructions as needed may be provided, one being positioned between each stage and the following stage.

It is obvious that the machine shown in Figure 5 can be adjusted in accordance with the adjustments found to be most desirable by the use of a test machine as previously described, or if desired, the machine shown in Figure 5 may be individually adjusted without utilizing any previous adjustments on a test machine.

It is also possible in practicing this invention to have fixed poles for the separator, whether of a single stage type or of a multistage type, for any given material or any range of materials of about the same characteristics. In this case the test machine would first be adjusted to secure the desired results for that particular material and thereafter the poles would be made in a fixed or unitary structure with the magnetic field structure of the machine and would not be adjustable. Also it is to be understood that the last stage or last stages of a multiple stage separator could have the fixed poles if desired.

It will be seen that a novel form of magnetic separator has been provided which may be constructed either as a single stage separator or as a multiple stage separator, and in which adjustments are provided whereby the poles may be adjusted towards or from each other, the overlap of the poles may be adjusted, and the angularity of the poles may be adjusted, the poles themselves having a socketed connection with the field structure, thereby minimizing losses at this jointed portion of the machine.

It is to be noted also that the feeding means is carried as a unitary structure by the upper pole and that the relative adjustment of this feeding means with respect to the upper pole is not affected by adjustment of the upper pole.

It will be seen also that the feeding means itself is adjustable to vary the rate of feed or the spacing of the feeding trough or member from the upper pole, and that tapping means or vibrating means for the non-magnetic shield plate is provided and is also individually adjustable as required.

In all forms of the invention the upper pole acts as a premagnetizing pole and the lower pole The separator, while it is adapted to operate upon widely different materials, nevertheless is highly effective in operating upon materials of relatively high reluctance.

The invention provides for the feeding of the material either into proximity to the upper pole or in contact with the bare upper pole and thereafter allowing the material to descend under the action of gravity after the magnetic portion of the material has been premagnetized by the upper or premagnetizing pole. The descending material freely falls past the pole tips and traverses the gap between the pole tips. The lower pole acts as a diverting pole for the premagnetized magnetic material and diverts the premagnetized magnetic material from the freely falling stream of the mixed material and thereby effects separation. The dividing member and the other means act to keep the separated material away from the remaining material; In the multistage separator the remaining material is fed to the next stage which may include either a shielded upper pole and a shielded lower pole, or may include a bare upper pole and a shielded lower pole as shown, for example, in Figure 5. It is apparent that the more highly permeable'material has been separated in the first stage, and that the remaining magnetic material is of still higher reluctance. Therefore it is fed intoa field of greater concentration than that of the first stage. This may be effected by increasing the actual field strength of the succeeding stages in a progressive order or may be effected by feeding the material delivered from the first stage into direct contact with the bare premagnetizing upper pole of the next stage, as has been shown in Figure 5. As many stages may be employed as needed and more than one stage having a shielded upper pole and more than'one stage having anunshielded upper pole may be, em-

succeeding stages may require a different adjustment from the feeding means of a preceding stage as a different type of material is being treated by a succeeding stage from that which was treated by the preceding stage. The independent adjustability of the feeding means is therefore desirable in a separator of this type and by having the feeding means for each stage carried by the upper pole of such stage, it is apparent that the exact adjustment of the upper and lower poles for any stage may be most easily obtained without disturbing the relative adjustment between the feeding means and theupper pole of such stage. This greatly facilitates adjusting the machine for the exact material t be separated by the machine.

Also it is to be noted that the adjustability of the vibrator and the adjustability of the feeding means with reference to the upper pole makes it possible to satisfy the exact requirements for any particular material.

It is to be noted further that the non-magnetic shields are adjustable to thereby provide additional flexibility for the machine.

All of these adjustments may be very rapidly made and do not interfere one with the other.

It is to be understood that wherever the expressions magnetic and non-magnetic material are used, that it is intended that these expressions shall not be specificially construed but shall be understood to mean materials having different reluctances-that referred to as magneticrmaterial having lesser reluctance than that referred to as non-magnetic material. intended to separate materials of different magnetic reluctance. and though the material separated is of higher permeability than the material from which it is separated, nevertheless that material from which it is separated may be slightly magnetic itself but of less permeability considerable-detail, it is to be understood that The separator is such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim: I

1. A magnetic separator comprising a field structure including an upper portion and a lower portion and having an energizing winding, an

upper and a lower V-shaped pole pivoted, respectively, to the upper and lower portions of the field structure with their tips spaced apart, whereby either or both of said poles may be angularly adjusted to increase or decrease the magnetic intensity and to restrict or disperse the lines of force at the space between the pole tips, feeding means for feeding a mixture of magnetic and non-magnetic material bodily attached to the upper pole and movable therewith to maintain a predetermined feeding position with respect to a point adjacent the tip of the upper pole, the material freely flowing past and in front of the tips of both the upper and lower poles, the magnetic material being premagnetized by the upper pole and being diverted inwardly by the lower pole while the material freely falls in space out of contact with any portion of the separator, and

means located below the tip of the lower pole for keeping the diverted material separate from the remaining material. a w

2. A magnetic separator comprising a field structure including an upper portion and a lower portion and having an energizing winding, an upper and a lower pole member having angularly adjustable V-shaped poles pivoted, respectively, to the upper and lower portions of the field structure, the tip of the upper pole overhanging the tip of the lower pole, feeding means for feeding a mixture of magnetic and. non-magnetic material to a point adjacent and in front of the upper pole, the materialfreely flowing in front of and past the tips of both the upper and lower poles, the

magnetic material being premagnetized by the upper pole and being diverted inwardly by the lower pole while the material freely falls in space V out of contact with any portion of the separator,

a non-magnetic shield plate carried by the lower pole and bodily movable with the lower polev and adjustable with respect to the lower pole,and means located below the tip of the lower pole for keeping the diverted material separate from the remaining material. v

3. A magnetic separator comprising a field structure including an upper portion and a lower portion and having an energizingv winding, an upper and a lower pol pivoted, respectively, to the upper and lower portions of the field structure, feeding means for feeding a mixture of magnetic and non-magnetic material to a point'adjacent the upper pole, said feeding means, being bodily carried by the upper pole, whereby adjustment of the upper pole does not affect the relation of the feeding means to the upper pole,the material freely flowing past the tips of the ,upper and lower poles, the magnetic material being premagnetizedby the upper pole and being'diverted by the lower pole, and means located below the tip of the lower pole for keeping the diverted material separate from the remaining material.

4. A magnetic separator comprising a field structure including a magnetizing winding, an upper and a lower pole both said poles being stationary during the operation of the separator, said upper pole being adjustable, feeding means carried by said upper pole and bodily moving as a unit with said upper pole when said upper pole is adjusted, and dividing means located below said lower pole.

5. A magnetic separator comprising a field structure including a magnetizing winding, an upper and a lower V-shaped pole each individually angularly adjustable and both said poles being stationary during the operation of the separator, adjustable feeding means carried by said upper pole and bodily moving as a unit with said upper pole when said upper pole is adjusted, said feeding means being independently adjustable with respect to said upper pole to permit the passage of material of different sizes between the tip of the upper pole and the feeding means and having means for varying the speed of feed of the material for varying the time of passage of the material through the separator, and dividing means located below said lower pole.

6. A magnetic separator comprising a field structure including a magnetizing winding, an upper and a lower pole adjustably carried by said field structure and having juxtaposed individually angularly adjustable V-shaped pole tips separated by a gap, both said poles being stationary during the operation of the separator, a non-magnetic shield extending across the gap and over the face of the lower pole and over the tip of the upper pole, feeding means carried by the upper pole for feeding material to adjacent the tip of the upper pole, said shield being hingedly and bodily carried by said feeding means and being adjustable to vary the air gap between the shield and the tip of the upper pole thereby varying the range of separation, said material freely falling under the influence of gravity across the gap and past the lower pole tip whereby the magnetic material will be diverted while the material is freely falling in space, and means located below the tip of the lower pole for keeping the diverted material separate from the remaining material.

'7. A magnetic separator comprising a field structure including a magnetizing winding, adjustable upper and lower poles carried by said field structure and having juxtaposed pole tips separated by a gap, a non-magnetic shield extending over the pole tips and across the gap feeding means including a vibrator for feeding material against said shield adjacent the upper pole tip, said material freely sliding along said shield and freely falling across said gap under the influence of gravity, the magnetic material being diverted by said lower tip, said feeding means being carried by said upper pole and being adjustable with respect to said upper pole, adjustable means carried by said feeding means for imparting vibration to said non-magnetic shield, and means located below said lower tip for keeping the diverted material separate from the remaining material.

8. A magnetic separator comprising a field structure including a magnetizing winding, adjustable upper and lower poles carried by said field structur and having juxtaposed pole tips separated by a gap, a non-magnetic shield extending over the pole tips and across the gap,

said non-magnetic shield being supported from said upper pole and being adjustable, feeding means including a vibrator for feeding material against said shield adjacent the upper pole tip, said material freely sliding along said shield and freely falling across said gap under the influence of gravity, the magnetic material being diverted by said lower tip, said feeding means being carried by said upper pole and being adjustable with respect to said upper pole, adjustable means carried by said feeding means for imparting vibration to said non-magnetic shield, and means located below said lower tip for keeping the diverted material separate from the remaining material.

9. A magnetic separator comprising a plurality of separating stages arranged one above the other and each comprising a premagnetizing upper pole and a lower diverting pole having juxtaposed pole tips; feeding means for each stage for feeding material adjacent the upper pole tip, the material freely falling under the influence of gravity past the lower pole tip whereby the less reluctant material is diverted from the remaining material; and a chute construction located between successive stages and having a first receiving compartment extending transversely across the separator for receiving the diverted material and a discharge apron for the said diverted material for discharging the said diverted material outwardly from the separator, and having a second receiving compartment extending transversely across the separator for receiving the remaining material, and having a plurality of spaced tubular delivery members extending downwardly from the second receiving compartment and passing through the said apron for delivering the said remaining material to the feeding means of the succeeding stage, the said diverted material passing along said apron between the said tubular delivery members.

10. A magnetic separator comprising a plurality of separating stages arranged one above the other and each comprising a premagnetizing upper pole and a lower diverting pole having juxtaposed pole tips; feeding means for each stage for feeding material adjacent the upper pole tip, the material freely falling under the influence of gravity past the lower pole tip whereby the less reluctant material is diverted from the remaining material; and a chute construction located between successive stages and having a first receiving compartment extending transversely across the separator for receiving the diverted material and a discharge apron for the said diverted material for discharging the said diverted material outwardly from the separator, and having a second receiving compartment extending transversely across the separator for receiving th remaining material, and having a plurality of spaced tubular delivery members extending downwardly from the second receiving compartment and passing through the said apron for delivering the said remaining material to the feeding means of the succeeding stage, the said diverted material passing along said apron between the said tubular delivery members, said chute construction having means below said tubular delivery members for spreading out the said remaining material into a thin sheet.

ROSWELL H. STEARNS. 

